A lot of good players have a "two burst" swing, where the shaft is seriously bent in this part of the swing, and where something similar happens around impact. It's related to lag pressure.
The combination of lag pressure excerted by right hand - and rope handling pull from the left arm - will put a significant amoung of Newtonian moment to the grip end of the club. (Force x length). And the work from this moment stresses and bends the shaft. And increase the clubhead sped as well. AND ENERGY IS STORED.
Image 2:
While it is biomechanical possible to maintain the clubhead speed through impact it is impossible to maintain the brute force moment from image 1 all the way through. And when the moment decreases , the shaft starts to release. And since the club is a highly resonant system with moderate inner damping, the club will now whip forward - as it does here. This is not an ideal occurence since it means that stored energy is released long before impact. It is kind of similar to the dreaded throwaway. But given how we are built it is perhaps unavoidable in a swing that starts hard and fast down.
Image 3:
Strange things may happen to the shaft at impact. But it seems to me like this player has a two-burst swing. That he was reloading the shaft. Or at least was trying to. But the forward bend of the bottom half of the shaft will work against his effort of adding an extra ooomph at impact.
All this shaft bending and releasing business is about stored energy. If the shaft doesn't fit the swing, chances are that the energy stored in the shaft is released at the wrong moment. Further, the s- shape of the shaft just before impact here suggests there's no chance that all the stored energy will be used to send the ball far away. The shaft seems to be loaded and unloaded at the same time at impact.
I believe this is the kind of image that proves that the shaft manufacturers still have an interesting challenge in securing a proper and controlled sequence of energy storage and release through the swing.
Other people have a "one burst" swing, where the moment applied at the club shaft increases gradually through impact. But we aren't able to load the shaft as much at impact and therefore the biggest shaft bends are usually seen in strokes like image 1-3 with a big wrist cock and aggressive down swing.
And then some people are using an almost pure rope handling technique throughout without any of these shaft loading bursts. In addition to the extensive shaft loading we see above, the rope is pulling the center of gravity. And since this isn't on the shaft axis it will cause shaft bend as well. In which case the mechanical properties of the shaft will have less influence on distance, but perhaps on direction.
The stiffness of the shaft has a profound influence of the timing of the shaft rebound. A stiff shaft will release faster than a whippy shaft, and every player that applies some moment to the shaft (lag pressure) at impact would want a shaft that releases in juust the right moment.
Very interesting and insightful post.
I took these pictures of Yoda and remember the procedure he was displaying. Ill leave it to Yoda to discuss in full but your observations are
very perceptive. He was laying it on real hard in release with an active right arm. The pictures dont reveal what the naked eye saw and ears heard. Like a war on the practice field.
While it is biomechanical possible to maintain the clubhead speed through impact it is impossible to maintain the brute force moment from image 1 all the way through. And when the moment decreases , the shaft starts to release. And since the club is a highly resonant system with moderate inner damping, the club will now whip forward - as it does here. This is not an ideal occurence since it means that stored energy is released long before impact. It is kind of similar to the dreaded throwaway. But given how we are built it is perhaps unavoidable in a swing that starts hard and fast down.
Thanks for your post, BerntR. Once again, I want to respond to this very important point.
1. The Clubshaft has inertia. Tipped-stiff or senior flexible, it has inertia.
2. At the same time, Centrifugal Force has a Line of Pull. That invisible line is from the #3 Pressure Point (first joint of the right forefinger) to the Sweetspot. This Lag Pressure Point Pressure (1-L #7) is what is driving the Club, not the Clubshaft.
3. The inertia of the clubshaft cannot keep up with the Centrifugal Line of Pull. Hence, it lags behind. This 'reverse' parabola (reverse in that the forward bend is counter-intuitive) made a dramatic appearance in Ben Hogan's first book, Power Golf. With the exception of Elbow Postion (Pitch versus Punch), the photo on page 97 of that book (hardcover version) is virtually identical with Image #2 (below) in your post.
If somebody could put that up, I'd appreciate it. Thanks!
Yoda - you wrote-: "At the same time, Centrifugal Force has a Line of Pull. That invisible line is from the #3 Pressure Point (first joint of the right forefinger) to the Sweetspot. This Lag Pressure Point Pressure (1-L #7) is what is driving the Club, not the Clubshaft."
Could you please expand on your argument?
I believe that CF is primarily driving the clubhead and the peripheral end of the club (where the COG is located) and not the entire club (which consists of a clubhead, peripheral shaft, central shaft and grip end of the shaft). I believe that the hands are simultaneously driving the grip end of the club while CF is driving the clubhead and peripheral end of the club.
Your argument seemingly presumes that when the club starts to release and CF comes into play, that the hands are no longer driving the club. However, the hands are still moving the grip end of the club during the process of club release and they are applying a pull force on the club (in a swinger) while the club is in the process of releasing - and this pull force (which is at an angle to the COG of the club) adds supplementary angular velocity to the clubhead and peripheral end of the club during the release process.
HK's endless belt keeps moving while the belt moves around the end pulley, and the club is still attached to the endless belt and therefore subject to its continuous motional forces.
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Add additional point - I was writing my post and I didn't see that Yoda was simultaneously modifying his post to read as follows-: "the lag pressure point is what is driving the club" (see next post #204). I originally thought that Yoda was stating that CF was driving the club.
I then have to slightly modulate my argument. I cannot understand what it means when one states that PP#3 is driving the club in a swinger's action. I thought that PP#3 only senses/monitors clubhead lag pressure and that it doesn't drive the club. The club is driven in a drag loading manner by the left hand pulling on the club in a swinger's action. The right hand doesn't apply push-pressure drive via PP#3 in a swinger's action.
By the way, we are presumably talking about a swinger's action because there is no centrifugal pull in play in a hitter's action.
Yoda will independently decide whether he wants to expand on his post - per my request.
Jeff.
Last edited by Jeff : 12-21-2008 at 11:52 PM.
Reason: add additional comment in response to Yoda's modified post.
Yoda - you wrote-: "At the same time, Centrifugal Force has a Line of Pull. That invisible line is from the #3 Pressure Point (first joint of the right forefinger) to the Sweetspot. This is what is driving the Club, not the Clubshaft."
Could you please expand on your argument?
I already did. Immediately after posting, I added the following text (in red) to my post:
"At the same time, Centrifugal Force has a Line of Pull. That invisible line is from the #3 Pressure Point (first joint of the right forefinger) to the Sweetspot. This Lag Pressure Point Pressure (1-L #7) is what is driving the Club, not the Clubshaft."
You could not have known this as you were responding, and I have so notified you by Private Message. Therefore, as I've advised, please take the added text into consideration and amend/edit your post as you see fit. Thank you.
I learned tonns about the golf stroke from the time before this site was launched. The flying wedges and the separation between swinging and hitting cleared up my head.
But I still think there are unclarities in TGM with regards to some of the mechanics involved. And the part that has some relationship to golf shafts have always struck me as odd.
I am wondering whether HK simply forgot to regard the club itself as an energy storage device. You can load it with energy, and it will release the energy when the moment it is subjected to is reduced under a certain threshold. Whether the energy is wasted or well spent is a question that is very similar of nature to the compression leak issue.
The shaft bending and release kind of works in the same way as a capacitor in an electric curcuit - you deliberately charge it, and it uncharges itself when the voltage is reduced below a certain threshold. And the centripetal force - the pure rotation - well - it stores energy pretty much the same way as an inductor. It will do it's best to keep the current constant.
(Modeling the golf mechanics as an electrical circuit could prove to be an interesting exercise, but perhaps not in this thread):
Originally Posted by Yoda
Thanks for your post, BerntR. Once again, I want to respond to this very important point.
1. The Clubshaft has inertia. Tipped-stiff or senior flexible, it has inertia.
2. At the same time, Centrifugal Force has a Line of Pull. That invisible line is from the #3 Pressure Point (first joint of the right forefinger) to the Sweetspot. This is what is driving the Club, not the Clubshaft.
I agree with what you're saying, but "rope pulling" isn't the only source of shaft bending. And probably not the largest either. If this was the case, we could all pick shafts on basis of swing speed alone.
I believe you are talking about the phenomen I described under the pure rope handling :
Quote:
And then some people are using an almost pure rope handling technique throughout without any of these shaft loading bursts. In addition to the extensive shaft loading we see above, the rope is pulling the center of gravity. And since this isn't on the shaft axis it will cause shaft bend as well. In which case the mechanical properties of the shaft will have less influence on distance, but perhaps on direction.
Well - I should have replaced COG with COI, but I hope you can see through that
For an Iron the centripetal force will flatten the lie angle of the club - pretty much as we see in your picture. ANd of course this isn't something we will se upfront at impact. And for a driver with COG well behind the sweeetspot it will also bend the shaft forward.
But since this kind of shaft bending is a function of the centripetal force - and that will pretty much be intact until impact - the shaft will not straighten or whip back midway. I sustain that a lot of players is applying a vicious newtonian moment with their hands on the shaft. So in many swings there are two sources of shaft bending. Actually three if you also consider the collision with the ball. If you apply your right hand #PP's and have the right hand below the left on the shaft - it is in a way - something that can't be avoided.
Quote:
3. The inertia of the clubshaft cannot keep up with the Centrifugal Line of Pull. Hence, it lags behind.
I'm not sure if I understand what you're saying here. Are you talking about inertia as in mass times distance squared?
Since the COG of the clubhead isn't in the extension of the shaft, the (virtual) rope is actually bent to begin with. The centripetal force will try to pull the rope to it's full length. And the shaft bends such that the distance between the hands and the COG of the clubhead increases.
Quote:
This 'reverse' parabola (reverse in that the forward bend is counter-intuitive) made a dramatic appearance in Ben Hogan's first book,[i] Power Golf.
I think we need to separate forward bend (because moment was applied to the grip end earlier and the shaft has kicked forward later) and downward bend caused by centripetal force + a COG offset in the clubhead. At 7-8 o'clock the two may be hard to separate on a face-to-face picture. The bend in picture 2 I commented seems way too eccessive to just be due to a COG pulling action though.
And there's absolutely no doubt whatsoever that picture 1 has a shaft bend that works agains the bending you will see from a pure rope pulling technique.
Like it or not; Some of the top ball strikers are bruteforcing the club to swing - at least in parts of their stroke.
But Zuback seems to be quite moderate in this department though. Maybe it is because he only has a moderate wrist cock at the top and in his early downswing. So I guess anyone who is willing to settle for around 200 MPH ball speed doesn't load the shaft in the early downswing
I added text to my post #202 immediately after posting (per my post 204) and while you were responding. Does it make a difference in your post? If so, please edit appropriately.
I was writing my post and I didn't see that Yoda was simultaneously modifying his post to read as follows-: "the lag pressure point is what is driving the club" (see next post #204). I originally thought that Yoda was stating that CF was driving the club.
And, Jeff, you were right!
Assuming the conventional Swinging motion -- which is what all these heretofore presented 'axis-string-ball' models have been about -- Centrifugal Force IS driving the Club. But, Jeff . . .
You've made a serious error.
Please re-read my post. You missed a word in your typed quote above, a very important word that I now will resurrect, return to its proper place, enlarge and highlight in red:
"This lag pressure point Pressure (1-L #7) is driving the club."
And the Lag Pressure Point Pressure is Centrifugal Force being transmitted through Pressure Point #3.
In both versions -- original or edited with additional information -- my post stands.
I don't see how you can definitively conclude that his his clubshaft will get under the handplane in the later downswing. I can agree that he may have a problem with his pelvis outracing his upper torso and arms and that he may not be able to easily square the clubface, which will result in pushed shots.
I do not know the golfer personally. He merely wrote and stated that he tended to loss his lag on certain swings and he thought that it mainly occurred when he reverse pivoted.
I agree that having a large amount of lag (like him) is not necessarily advantageous if he cannot complete his swing on-plane in a perfectly synchronised manner.
Jeff.
I agree with you about what your stating. I think people just get in love with the look of lag. Lag in the right places is what we would be loooking for.
Yoda - you wrote-: "This lag pressure point Pressure (1-L #7) is driving the club."
The Lag Pressure Point Pressure is the result of Centrifugal Force transmitted through Pressure Point #3."
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I certainly don't understand your viewpoint.
I believe that CF only comes into play in earnest when PA#2 passively releases (left wrist uncocks passively), and the club releases.
In a swinger the club is loaded against PP#3 at the end-backswing - when the clubshaft is parallel to the ball-target line. At that time point, the only pressure felt at PP#3 is due the weight of the club. Then, during the early downswing, the left hand is pulling the club down to the ball (while the left arm is kept loaded against PP#4 via the pivot-drive). Under those conditions, the sense of lag pressure felt at PP#3 increases because the clubhead has inertia and resists following the hands - it "feels" like one is leaving the club at the top while the entire power package is being pulled down intact to waist level via the lower body shift movement. I don't believe that there is any CF in play during the early downswing because the hands are moving along the straight line portion of the U-shaped hand arc. If the hands are moving more-or-less in a straight line, then there is no centripetal acceleration of the hands, and therefore no need for a counterforce (a CF). During this phase of the swing, I cannot understand how CF can be driving the club via lag pressure at PP#3.
Then, when the hands move around the rounded curve of the U-shaped hand arc, the hands are moving in a circular arc that has a small radius. If the hands are tracking along a hand arc of small radius then the hands are traveling at an acute angle relative to the COG of the clubshaft and that induces the clubshaft to release with great speed (and this represents the CF release phenomenon). The clubshaft releases because it develops angular velocity, and the angular velocity is acquired because the direction of the pulling force at the grip end of the club is at angle to the COG of the club.
nmgolfer explains the release phenomenon in his html document.
From the delivery position (3rd parallel) to impact, the club releases by 90 degrees (left wrist uncocks 90 degrees). During that time period, lag pressure sensed at PP#3 should theoretically decrease for a given degree of hand speed - because the left wrist is uncocking. However, an experienced golfer maintains a sense of near-constant lag pressure at PP#3 by ensuring that the right elbow straightens with sufficient isotonic force that allows the straightening right arm to keep up with the left arm (and allows the right hand to keep up with the left hand). In other words, the degree of lag pressure sensed at PP#3 is the result of the interplay of a number of biomechanical phenomena that are occurring simultaneously - i) the left hand is being driven around the small pulley of the endless belt due to the release of PA#4 which drives the left arm towards impact; ii) the speed of left wrist uncocking (which occurs passively secondary to the speed of CF release of the club); and iii) the speed of right elbow straightening which allows the right hand to keep up with the left hand. In this scenario, - PP#3 senses lag pressure, but does not drive the club. I think that two forces are driving the club at this stage of the downswing - i) the left arm pulling the left hand towards impact due to release of PA#4 => left hand pulls the grip end of the club continuously along the endless belt track; ii) CF that causes the passive release of PA#2. However, because the release of PA#2 is passive and activated by the left hand pull action at the grip end of the club (with no push-force from the right hand), then it can be said that the source of all power driving the club is essentially derived from a left hand pull action where the left hand travels along a circular arc (around the end pulley of the endless belt system). It is the left hand that drives (pulls) the club during the downswing in a swinger's action and the CF release phenomenon is simply activated by the left hand pull action (according to the principles of the double pendulum swing model). I have no idea what you mean when you state that lag pressure sensed at PP#3 drives the club, and that the lag pressure is derived from the CF acting through PP#3.
Yoda - you wrote-: "This lag pressure point Pressure (1-L #7) is driving the club."
The Lag Pressure Point Pressure is the result of Centrifugal Force transmitted through Pressure Point #3."
-----------------------------------
I certainly don't understand your viewpoint.
I believe that CF only comes into play in earnest when PA#2 passively releases (left wrist uncocks passively), and the club releases.
In a swinger the club is loaded against PP#3 at the end-backswing - when the clubshaft is parallel to the ball-target line. At that time point, the only pressure felt at PP#3 is due the weight of the club. Then, during the early downswing, the left hand is pulling the club down to the ball (while the left arm is kept loaded against PP#4 via the pivot-drive). Under those conditions, the sense of lag pressure felt at PP#3 increases because the clubhead has inertia and resists following the hands - it "feels" like one is leaving the club at the top while the entire power package is being pulled down intact to waist level via the lower body shift movement. I don't believe that there is any CF in play during the early downswing because the hands are moving along the straight line portion of the U-shaped hand arc. If the hands are moving more-or-less in a straight line, then there is no centripetal acceleration of the hands, and therefore no need for a counterforce (a CF). During this phase of the swing, I cannot understand how CF can be driving the club via lag pressure at PP#3.
Then, when the hands move around the rounded curve of the U-shaped hand arc, the hands are moving in a circular arc that has a small radius. If the hands are tracking along a hand arc of small radius then the hands are traveling at an acute angle relative to the COG of the clubshaft and that induces the clubshaft to release with great speed (and this represents the CF release phenomenon). The clubshaft releases because it develops angular velocity, and the angular velocity is acquired because the direction of the pulling force at the grip end of the club is at angle to the COG of the club.
nmgolfer explains the release phenomenon in his html document.
From the delivery position (3rd parallel) to impact, the club releases by 90 degrees (left wrist uncocks 90 degrees). During that time period, lag pressure sensed at PP#3 should theoretically decrease for a given degree of hand speed - because the left wrist is uncocking. However, an experienced golfer maintains a sense of near-constant lag pressure at PP#3 by ensuring that the right elbow straightens with sufficient isotonic force that allows the straightening right arm to keep up with the left arm (and allows the right hand to keep up with the left hand). In other words, the degree of lag pressure sensed at PP#3 is the result of the interplay of a number of biomechanical phenomena that are occurring simultaneously - i) the left hand is being driven around the small pulley of the endless belt due to the release of PA#4 which drives the left arm towards impact; ii) the speed of left wrist uncocking (which occurs passively secondary to the speed of CF release of the club); and iii) the speed of right elbow straightening which allows the right hand to keep up with the left hand. In this scenario, - PP#3 senses lag pressure, but does not drive the club.
Yes, Jeff, this is correct. Pressure Point #3 does not drive the Club. Centrifugal Force drives the Club.
Originally Posted by jeff
I think that two forces are driving the club at this stage of the downswing - i) the left arm pulling the left hand towards impact due to release of PA#4 => left hand pulls the grip end of the club continuously along the endless belt track; ii) CF that causes the passive release of PA#2. However, because the release of PA#2 is passive and activated by the left hand pull action at the grip end of the club (with no push-force from the right hand), then it can be said that the source of all power driving the club is essentially derived from a left hand pull action where the left hand travels along a circular arc (around the end pulley of the endless belt system). It is the left hand that drives (pulls) the club during the downswing in a swinger's action and the CF release phenomenon is simply activated by the left hand pull action (according to the principles of the double pendulum swing model). I have no idea what you mean when you state that lag pressure sensed at PP#3 drives the club, and that the lag pressure is derived from the CF acting through PP#3.
You have answered your own question: Centrifugal Force drives the Club.
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